Organic structures from spectra

What is the molecular weight of the following compound based on the mass spectra?

• 43

• 101

• 129

• 174

How many signals does the aldehyde (CH₃)₃CCH₂CHO have in ¹H NMR and ¹³C NMR spectra?

• five ¹H signals and six ¹³C signals

• three ¹H signals and four ¹³C signals

• five ¹H signals and four ¹³C signals

• three ¹H signals and six ¹³C signals

Which of hydrogens a-d in the following molecule gives a triplet signal in a normal ¹H NMR spectrum? 

• hydrogen a

• hydrogen b

• hydrogen c

• hydrogen d

Which of (a)-(d) indicates the correct order of carbon chemical shifts of the four carbons of the following compound.

• C_Me < C2 < C3 < C1

• C_Me < C3 < C2 < C1

• C_Me < C2 < C1 < C3

• C_Me < C1 < C2 < C3

A carbonyl group will cause a sharp dip in IR spectrum at about ____ cm^–1.

• 1700

• 2800

• 4300

• 1200